Electronic digital computers



Dec. 6, 1955 w. K. ERGEN ELECTRONIC DIGITAL COMPUTERS Filed May 18, 194e INVENTOR WILLIAM K- E EEN ATI'ORNEY United States Patent' annees ELECTRONIC mGrrAL COMPUTERS William K. Ergen, Oak. RidgeV Tenn., assignor, by mesne assignments, to the. United States. of America as represented by the, Secretary of theAir Force Application May 18', V1948', SerialI No. 27,7-77

7 Claims.` (Cla 23S-61) The coeicients si and di are either l or 0.

More specifically, the device refers to a straight line computer for an aircraft navigational system known as Shoran Reconnaissance. The. Shoran system measures the distance r1 of an aircraft from a base station S1 and it likewise measures the distance rz of the same craft from v another base station S2. The distance measurements are carried out by measuring thetime intervals required for pulses of electromagnetic energy to travel from the aircraft to the base station and back.

The present device is based on a modication of Shoran, which consists in measuring the above named time intervals by means of electronic counters. Each counter contains a chain of multivibrator circuits or stages and every stage has two stable states. One of these states. is` called the l-state and the other state is the Of-state.

The time intervals are measured in units. determined by the crystalfrequency in thecounter, and with special high speed counters these units may be l07 seconds, corresponding to about V100 mile in distance. T hel number of units in the time interval or distance to-be measured can then be expressed in the binary system, in analogy to (l) and (2). to one of the powers 2i. the 0-state dependent on whether the corresponding Coefficient of 2i is one or zero.

Instead of measuring the distances rr and r2 it is proposed to measure S=r1 +r2, and D=r2'r1=. (r2 is assumed to be greater than r1, which alwa'ysfcan` be accomplished since it is arbitrary which station 'is called Si and which is Sz.) The sum S can be' obtained easily by starting the counter by the pulse' emitted from the aircraft, stopping it by the pulse returning from` S2', starting it again, without resetting, by the pulse emitted from the Craft, and. stopping it when this pulse returns from S1. The diiferencecan be obtained in an analogous way with the only modification that ri is -subtracted from, rather than added to, r2. Or, if S1 and S2. are interrogated simultaneously the counter can be started by the pulse Each stage in each chain corresponds The stage is in the l-state or ICC 2 returningy from S1 and' stopped bythe pulse returning from S2;

In any case, there will be one chain, the S-chain, the stages oflwhi'ch are in the lstate or O-state dependent the coeilicients si of the binari/ expression (l) `for the sum ri-l-rz. There also is anothe clia'iri, the D'chaiti, the stages ofwhi'ch are inA the state prescribed' by` the 6o#A elicients di of the binary expression (.2) for the diife'r'enc The purpose ofthe computer ofthe present invention consists in determining whether the craftis on a predey termined lstraight line. Thepossible straight lines are conned to those perpendicular to the line between the two base stations. The equation of these perpendicular lines is a quadraticy equation in the bipolar coordinates r1 and r2, whereas the equation of a straight line in bipolar coordinates is, in general, a quartic equation. The quadratic equation of the perpendicular lines is vraz--rL--A SD=A (3') where A =ak2k (4) It =O is a predetermined constant depending on the. distance between the two base stationsl and on the distance. of one base` station from the desired line.

Briefly, the computer functions to determine whether the craftison the desired straight line, or, mathematically speaking whether ,(3 is. fulfilled. The determinationv is made, on the basis of the, information set into S.- and D'- chains of multivibrators.

There are two printer chains? Ps. and PD associated with thev counter chains, Si and D. `Thesep-rinter chains consist of type 6AS6.. tubes eachA of which. is connected to one multivibrator of S -or D.. The 6AS6 tube is completely blocked ifv the, corresponding multivibrator is in the O-state, but if the multivibrator isy in the l-state, then the 6AS6 can be. unblocked by a suiciently positive voltage on the control grid. The main. purpose of the tubes of these printer chainsY consistsin controlling the current through a. set of styluses (not, shown), which rest on fac'- simile paper. Each l6AS6 tube controls one stylus. If current flows through one of these styluses a dot is made on the paper. Thus,., if positive voltage is` applied to the control grids. of the 6AS6 tubes, dotsv will be4 printed by those styluses, whichl are. controlled bya 6AS6Y tube, which is connected to. amultivibrator in the 1 position. No dots will bemade bythe blockedV 6AS6 tubes, that are those which correspond to multivibrators; in the zero position. v Thus, the binary numbers S andl D are printed on the, facsimile paper. These printing styluses, and, their operating elements are not shownv for the reason that they are not a part. ofy the present invention.

The printer chains can also be used for computing purposes, and it is a primary aim of the present invention to accomplish the computing, with a minimum of additional lowingf description` considered in: connection with the: anh Y compan-ying drawingand,A its scope is indicated. by' the Y appended claims.

The single iigure of the drawing is, for the most part, a wiring diagram of the improved straight line computer of the present invention. Y

In this igure are shown (l) and S counter including trigger circuits V1 to V8 which are connected in tandem, that is, in cascade, and on which is established the value rz-l-rr, and (2) a D counter including trigger circuits V9 to V16 which are connected in cascade and on which is established the value of rz-ri.

The trigger circuits V1 to V16 are each of a well known type including a pair of triodes which 1) have their common cathode grounded, (2) have operating potential applied to their anodes and 11 from a +B lead 12 through a common resistor 13 and separate resistors 14 and 15, (3) have the anode of each triode connected to the grid of the other through a resistor 16 or 17 which is shunted by a capacitor 18 or 19, and'(4) have bias potential applied to their grids through a resistor 20 or 21 from a lead 22 or 23. The above numerals are applied only to the circuit V1 but it will be understood that they would be analogous for the other trigger circuits V2 to V16. By making the lead 23 momentarily more positive than the lead 22, the trigger circuits V1 to V16 may be established in their zero count or standby condition with current conduction in the right hand triode of each trigger circuit.

As is well known, such trigger circuits are stable with current conduction in either ofltheir anodes, and current conduction is transferred from one to the other of the anodes in response to the application of a negative potential pulse to the junction point 24 between the common anode resistor 13 and the separate anode resistors 14 and 15. These negative pulses are applied to V1 and V9 through a coupling capacitor 29, and each of the followtf1 in the binary numerical system, since each stage receives v one negative pulse for every two such pulses applied to the preceding stage, (2) each of the trigger circuits V1 to V16 is in a binary 0 condition when current conduction is in its right anode and is in a binary 1 condition when current conduction-is in its left anode, and (3) the numbers or values established in the counters are to be read from right to left. For example, with trigger circuits V1, V4, V6 and V7 in a binary l condition, and V2, V3, V5, and V8 in the 0 condition the established binary value is 01101001 which is equal to 105 in the decimal numerical system.

The negative pulses counted by the counters V1 to V8 and V9 to V16 are supplied from an oscillation generator 25. The circuits by which the supply of such negative pulses to each counter is controlled are of the same design. Thus, each of the control circuits includes a trigger circuit V17 of the type previously described and a pentode P1 which has one of its grids 26 connected to the anode 27 of the trigger circuit V17 and has its other grid 28 connected to the oscillation generator 25. With these connections, oscillations are supplied through the coupling capacitor 29 to the point 24 of the multivibrators V1 or V9 only when current conduction is in the anode 30 of the trigger circuit'V17.

Negative pulses for operating the control circuit are applied through a lead 31 and a coupling capacitor 32.

Thus, in the case of the S counter, a negative pulse is applied to the lead 31 when a first pulse is transmitted from the aircraft, a negative pulse is applied 4to the lead 31 when this rst pulse is returned from the station S1 to the aircraft, a negative pulse is applied to the lead 31 when a second pulse is transmitted from the aircraft, and a negative pulse is applied when this second pulse is returned from the statiton Sz to the aircraft. As a result, the number of constant frequency pulses counted by the S counter is proportional to rz-l-rl,

Y l 4 which is the sum of the distances from the aircraft to the two stations S1 and S2.

The operation of the D counter is similar to that of the S counter with the exception that the negative pulses applied to its input lead 31 are such as to establish in it a count proportional to rz-r1 which is the difference between the distances from the aircraft to the two stations.

The values thus set into the S counter are scanned through the medium of (1) a printer chainPs which includes the pentodes P2 to P9, (2) a matrix chain Ms which includes the Y-connected networks M1 to M8, and a scanning chain Bs which includes the trigger circuits V18 to V20.

The values set into the D counter are scanned through the medium of a printer chain PD, a matrix chain MD and a scanning chain BD.

Pulses for operating the scanning chains Bs and BD are supplied from a generator 33 through a lead 34 to the common anode resistor terminal of the trigger circuit V18 and through a lead 35 to a similar point of the trigger circuit V21. As explained below, the connections between the scanning chains and the Y`connected matrix networks are such that the S counter is scanned in one direction and the D counter is scanned in the opposite direction.

Each of the printer chain pentodes P2 to P17 includes (1) a cathode 36 which is grounded, (2) a grid 37 which is connected to ground through a suitable resistor 38 and to the common terminal of one of the Y-connected networks through a suitable capacitor 43, (3) a screen grid 39 which is connected to the com mon terminal of a resistor 40Vand a capacitor 41, (4) a suppressor grid 42 which` is connected through one of the resistors (for example, the resistor 17) to one of the anodes (the anode 11) of the counter chains, and (5) an anode 44 which is connected through a common anode resistor 45 to the +B lead 12. (Numerals are shown only for the pentode P2 but apply similarly to the pentodes P3-P17.)

With these connections, each of the pentodes P2 to P17 conducts only when (l) the trigger circuit to which its grid 42 is connected is in a binary (l) condition and (2) the outer terminals 46, 47 and 48 (these numerals are only shown for M1, but apply to the other networks M2-M16 as well) of the corresponding Y-connected network are all at their most positive potential.

When any of the pentodes P2 to P9 conduct current, a negative pulse is produced at a lead 49 due to the vol tage drop of the resistor'45. When any of the pentodes P10 to P17 conduct current, a similar negative pulse is produced at a lead 50. From this, it follows that the leads 49 and 50 are simultaneously negative only when the simultaneously scanned trigger circuits of the S and D counters are in a binary l condition i. e. when cur rent conduction occurs in the left hand anodes of such trigger circuits.

The connections between the scanner chain Bs and the matrix network chain Ms are such that the S counter chain is scanned in a direction from the lowest ordcr (V1) to the highest order (V8). The connections between the scanner chain BD-and the matrix network chain Mn are such that the D counter is scanned from the highest order (V16) to the lowest order (V9).

For example, when current conduction goes over to the right hand anodes of the trigger circuits V18, V19 and V20 of the scanning chains Bs, the terminals 46, 47 and 48 of the network M1 are all positive and the trigger circuit V1 is scanned. When the next pulse is applied from the generator 33 through the lead 34 to the common anode resistor terminal 'of the trigger circuit V18, current conduction is transferred to its left anode, the terminals 46, 47, and 48 of the matrix network M2 are all positive and the trigger circuit V2 is scanned. In a similar way, the trigger circuits V1 up to V8 are successively scanned ande thee triggerTA circuits V16 down to V9y are successively scanned.t

' -It will`be'y noted that* the right hand anodev of. the trigger circuit V`20i-is connectedtl) through a lead'51 and a capacitor 52 to theY grid253lof a' trigger circuit AV24, (2) through a lead54 and acapa'citor 55 to the right hand grid-of the trigger circuit V21` and (3 )v through a lead 56 to' a'l right shiftingd'evice referred" to hereinafter.Y

Thev right hand anode of` the trigger circuit V23 is connected throughA a leadf59 anda capacitor 60 to the right handlgrid61'of the trigger: circuit V24 which is like the trigger circuits V1 to V23'previously considered. As a result, the trigger circuit V24 has current conduction transferred' (1)VV to its. anode' 62y Wh'enf'the right'haud triode ofthetrigger circuit V20 fakes current and (2)' to its anode 63 when the right hand anode of the trigger circuit V23 Ytakes current,

Itv will be noted thatthe anode 62 is connected through a lead 64to the' anodeof a" rectifier Y65, that the leads 49 and 50 are similarly connected tothe anodes of rectifersy 66 and67 and that theY cathode's of thesev three rectitiers have a common lead 68k which is connected to groundthrough a resistor 69.

When any of the leads 49, 50 or .64 is at apositive potential, the`input capacitor 72 ofy the C0 counter is charged: When all the leads 49,V 50,.arrd 64 are negative, (l) the' capacitor 72 is discharged through the resistor 71, the lead 70and the resistor 69, (2) a negative pulse is produced at'the common anode resistor terminal of the trigger circuit V25V and (3) a count of binary l is set up in the counter C5.

The Equation (3.) may be written,.using (l), (2) and Since si an'ddj are either lor O, the product sid; is equal to l', if both si and drare eqaul to 1. If either si or d5, or both, are 0, then sidj is zero. The coeiicient of 2k`on the left side of (5) is the number of nonvanishing products sid; with z'-{j=^k, or, in other words, the number of such products in which neither si nor dj vanishes.

Electronically, the chains Ps and PD are scanned in such a Way that'the tube corresponding to si is scanned simultaneously with the tube corresponding'l to Then, one counts the number of coincidences, in which both the si and djwere equal to one.

The output counter C5 counts the number of such coincidences. This is accomplished by4 means of the' two crystal rectiers 66' and 67. If either of the leads 49 or 50 is athigh positive potential,` the lead 70 will be at the same potentialY as the crystals conduct in thev direction 49 to 70 and'50'to 7,0,.butjnot in the opposite direction. However, if both 49v and 50 go more negative, due tora coincidence of negative pulses from the leads v49 and'50, then the high resistor 69 will discharge the Vcoupling condenser 72 and a negative pulse will enter C6. l

The function of the trigger .circuit V2`4 and the rectiser 5s will be illustrated by the example k=t+j=10- t In the following table, each vertical column gives the i and j values which are scanned' simultaneously:

Evidently, the scanningI of the i and j values on the rightfof the vertical line is-what gives the desired result, as the i and j values'add upI to 10. However, 011 the left of the verticalline, the ipand j.values add up'to 2, and'V some means have to bel provided to `block out the counter C o While the and j values on the:` leftiof the l6 A vertical lineare scanned. This is accomplishedby the trigger circuit V24 and the rectifier 65.

The trigger circuit V24'has' two stable states. Inoue of these states, it makes the anode of. therectifierGS' positive,v and, even if there is a coincidence betweeii two pulses out of the PD and Ps chains,- this will prevent a negative pulse from going into C6. Thus, in this state of the trigger circuit V24, C5 is blanked out.- In the other state ofthe trigger circuit 24, the cathode of the r'ectiiier 65 is relatively negative and a pulse canAV enter C6.

The transition of the trigger circuit 24 from one of its stable states into the other is caused by the negative pulses obtained from the scanner chains Bs and Bn as previously explained. More specic'ally these pulses are obtained from the tubes most to the right of each of these chains, and they occur when the right half of the tube goes from the blocked to the unblocked state. Thus one such pulse occurs when i goes from 7 to 0 and the other when j goes from 0 to 7.

The operation starts with the highest k (14), and then goes successively to lower k. In order to lower k by one unit, the above mentioned pulse which is generated after i=7 is scanned, is also fed to the input of the scanning chain BD. This advances the latter chain by 1 unit, without affecting the chain Bs. The just mentioned pulse at the output of chain Bs occurs somewhat later than the pulse which is fed tol the input of this :chain and which is one of the pulses at the output of the generator 33. This delay is due to the time constants inthe chain. The delay is used to avoid interference of the pulse from the output of Bs with the other pulses fed into BD. Of course, the delay should not1be so large that the pulse at the output of Bs occurs simultaneously with, ory later than, the next pulse fed into BD.

Thus, the z' and j values are scanned in the following order with the counter Co blanked out While thenumbers in the boxes are scanned: l

@7 @in 567 012s 4567 34567 012345670 kx. n.

and so on.

The'transition at point x is as follows: While i goes from 7 to O, a negative pulse is generated which blanks out C6. j is simultaneously reduced by one unit, which gives j=0. The negative pulse from Bs advances janother unit, to j=7, and that generates anotherV .negative pulse, which unblocks C0. At point y, two pulse'sare fed to the trigger circuit V24, one originating in Bs by the transition from 7 tol 0,' and the other originating in BD from the transition from 0 to 7; These pulses'have to be somewhat separated in time in orderto allow the trigger circuit V24 to ilip'over and'backr` l Simultaneously with the advancing of the'chain'Bn, the' pulse from the output of Bs also operates through the lead 56a right shifting device whichtransfers the information set into a stage, or tube, of C6 into the next higher order stage, or tube, to the right'in this chain. Thus, ifratube in C6 is in the l-state before the right shifting occurs, the tube next to the right will be in the l-state after the right shifting. Similarly,.a zero state in oneof the tubes of C6Y causesl the next tube to the right to go to zero" after the right shifting'. Various right shifting devices are known to the art,` and they are not part of the invention. Instead of introducingA directly, it is best to use q B=`3b'2'c =-K-A k=0 where K is the'nu'r'nber of pulseswhichi return the counter C6 to its original position. (For an 'rr-stagebinary counter, K=`=2). The bkare introduced bymeansof thek switchesfSw-each;

switch corresponds to one bk. The switches corresponding to bk=l are connected to the bus bar E and those corresponding to bk= are open. A negative pulse is applied to E, and thus one unit is fed into each multivibrator of Co which corresponds to a bk=l. This is done at the end of the operation during which the product SD is set into the counter.

Then, in effect, the output counter is set to SD-l-B, or SD-A-l-K. Since K just runs the counter through once, it does not affect the reading, and the counter setting is equivalent to SD-A. This should be zero if the craft is on the desired straight line, and Equation 3 is fulfilled. A suitable indicator, for instance one involving the familiar neon lamps connected across the resistors of the multivibrator circuits V25, V26, etc., may be used to indicate this fact.

What the invention provides is a straight line computer which (l) is based on a navigation system wherein printer chains are utilized to record the positional data of a moving object and (2) functions to provide a visual indication of such positional data.

What is claimed is:

l. The combination of first and second counters each including a plurality of stages which are connected in cascade and are operable to either a binary O or binary 1 condition, means for establishing a first count in said first counter and a second count in said second counter, first and second scanning chains each including a plurality of cascade connected stages, means interconnecting said first scanning chain with said first counter to produce a pulse in response to the scanning of each stage of said rst counter which is in a binary l condition, means interconnecting said second scanning chain and said second counter to produce a pulse in response to the scanning of each stage of said second counter which is in a binary 1 condition, and means responsive to a coincidence ofand connected to receive said pulses.

2. The combination of first and second counters each including a plurality of stages which are connected in cascade and are operable to either a binary 0 or binary l condition, means for establishing a first count in said first counter and a second count in said second counter, first and second scanning chains each including a plurality of cascade connected stages, means interconnecting said first scanning chain with said first counter to produce a pulse in response to the scanning of each stage of said first counter which is in a binary l condition, means interconnecting said second scanning chain and said second counter to produce a pulse in response to the scanning of each stage of said second counter which is in a binary l condition, an output counter, and means responsive to said pulses and to predetermined conditions of said scanning chains for establishing in said output counter a count which is equal to the product of said first and second counts.

3. The combination of rst and second counters each including a plurality of stages which are connected in cascade and are operable to either a binary 0 or binary l condition, means for establishing a first count in said first counter and asecond count in said second counter, first and second scanning chains each including a plurality of cascade connected stages, means interconnecting said first scanning chain with said first counter to produce a negativetpulse in response to the scanning of each stage of said vfirst counter which is in a binary 1 condition, means interconnecting said second scanning chain and said second counter to produce a negative pulse in response to the scanning of each stage of said second counter which is in a binary 1 condition, a first rectifier connected to have applied to its anode the negative pulses produced by the scanning of said first counter, a second rectifier connected to have applied to its anode the negative pulses produced by the scanning of said second counter, a trigger circuit operable toa first current conductive condition in response to each Vcompletion of the operating cycle of said first scanning chain Yand toa second current conducting condition in response to each completion of the operating cycle of said second scanning chain, a third rectifier connected to have a negative potential applied to its anode only when said trigger circuit is in said second current conductive condition, means responsive to each completion of the operating cycle of said first scanning chain for changing the state of said second scanning chain by one digital position, an output counter, and means interconnecting the cathodes of said rectifiers with the input of said output counter to apply a negative pulse thereto only when. al1 the anodes of said rectiers are at a negative potential.

4. The combination of first and second counters each including a .plurality of stages which are connected in cascade and are operable to either a binary 0 or binary l condition, means for establishing a first count in said first counter and a second count in said second counter, first and second scanning chains each including a plurality of cascade connected stages, means interconnecting said first scanning chain with saidfirst counter to produce a negative pulse in response to the scanning of each stage of said first counter which is in a binary l condition, means interconnecting said second scanning chain and said second counter to produce a negative pulse in response to the scanning of each stage of said second counterwhich is in a binary 1 condition, a first rectifier connected to have applied to its anode the negative pulses produced by the scanning of said rst counter, a second rectifier connected to have applied to its anode the negative pulses produced by the scanning of said second counter, a trigger circuit operable to a first current conductive condition in response to each completion of the operating cycle of said first scanning chain and to a second current conducting condition in response to each completion of the operating cycle of said second scanning chain, a third rectifier connected to have a negative potential applied to its anode only when said trigger circuit is in said second current conductive condition, means responsive to each completion of the operating cycle of said first scanning chain for changing the state of said second scanning chain by one digital position, an output counter, means interconnecting the cathodes of said rectifiers with the input of said output counter to apply a negative pulse thereto only when all the anodes of said rectifiers are at a negative potential, and means responsive to each completion of the operating cycle of said first scanning chain for initiating an operation, after which each individual stage of said output counter is in the binary 0 or 1 condition, depending on whether the stage of order next lower to that of said individual stage was, before the operation, in the 0 or 1 condition.

5. The combination of first and second counters each including a plurality of stages which are connected in cascade and are operable to either a binary 0 or binary l condition, means for establishing a rst count in said flrst counter and a second count in said second counter, means operable to scan said first and second counters so that the orders of said counters are scanned in opposite directions, an output counter, and means responsive to said scanning means for producing in said output counter Va count which is equal to the product of said first and second counts.

6. The combination of a counter including a plurality of stages which are connected in tandem and are each operable to a binary 0 and a binary l condition, a pentode chain including a plurality of pentodes having operating potential applied to their anodes through an impedance element common to all of said anodes, means interconnecting each of said counter stages with a first grid of a different one of said pentodes so that a positive potential is applied to said first grid only when the stage to which it is connected is in a binary l condition, a scanning chain including a plurality of stages which are connected in cascade and are each operable to either of two current conductive conditions, and a matrix chain including a plurality of networks each having one terminal connected v chain including a plurality of pentodes having operating 10 potential applied to their anodes through an impedance element common to all of said anodes, means interconnecting each of said counter stages with a rst grid of a diiferent one of said pentodes so that a positive potential is applied to said iirst grid only when the'stage to 15 which it is connected is in a binary l condition, a scanning chain including a plurality of stages which are connected in cascade and are each operable to either of two current conductive conditions, a matrix chain including a plurality of networks each having one terminal connected to a second grid of a diierent one of said pentodes and having other terminals connected to said scanning chain so that Y the stages of said counter are successively scanned in response to one operating cycle of said scanner chain, and an output lead which is common to the anodes of said pentodes and at which a negative pulse is produced in response to each scanning of a counter stage in a binary l condition.

References Cited in the iile of this patent t UNITED STATES PATENTS 2,404,047 Flory July 16, 1946 2,404,697 Desch July 23, 1946 2,409,689 Morton Oct. 22, 1946 2,429,227 Herbst Oct. 21, 1947 2,436,963 Grosdol Mar. 2, 1948 2,445,215 Flory July 13, 1948 

